[orwin]

There is a lot of really good advices here about when to do TDD and how to do it, so i would only reiterate earlier comments.

My personal experience is that i start TDD once my project is "mature" enough that the next upgrade/addition can be put at two different place easily enough and i don't know where is the best place to do it. Basically, on my latest project, i asked myself something like: "is this part of this class method, or should the main loop take care of it?". That's where i started completing tests to 90% coverage (main loop + pagination mocks were skipped, ideally i could've reach 95% but laziness caught up) and started TDD. In the end, i still made the wrong choice and added my change to the class method, only to change it back two weeks ago (or roughly six month later). Here, TDD didn't help me to make the best software architecture choice, but having to write test first for this part of code made me decouple it from the method i originally put it in, and allowed me to made a architecture change in less than an hour.